Surveys repeatedly show that people simultaneously believe that climate change poses serious risks, and also that it is safe to delay reductions in greenhouse gas emissions to a level sufficient to stabilise atmospheric greenhouse gas concentrations, until there is greater evidence that climate change is harmful.
US policymakers, too, argue that it is prudent to “wait and see” whether climate change will cause substantial economic harm before undertaking policies to substantially reduce emissions.
This wait-and-see attitude is based on simple but serious misconceptions. It grossly underestimates the substantial delays in the climate’s response to the consequences of human emissions (“anthropogenic forcing” – that is, generated by, or the result of, human activity). And it presumes that climate change can be reversed quickly when harm becomes evident.
We can see why, by imagining the earth as a huge bathtub. The concentration of greenhouse gases in the atmosphere is like the water in the bathtub. Flowing from the faucet, or tap, are human-generated greenhouse gas emissions. The drain flow out of the bathtub is the rate at which carbon dioxide is removed from the atmosphere (by biomass, the ocean, and other carbon sinks).
Climatologists agree that humans are putting greenhouse gas into the atmosphere at almost twice the rate that natural processes can remove them. The bathtub is filling twice as fast as it is draining.
Even if policies to mitigate climate change caused greenhouse gas emissions to fall, atmospheric greenhouse gas concentrations would continue to rise until emissions fell to the removal rate.
Greenhouse gas concentrations can fall only if emissions drop below removal levels. Warming would continue until atmospheric concentrations decreased enough, and global mean temperature rose enough, to restore net radiative balance. Global mean surface temperature would then peak, and climate changes such as sea level rise from ice melt and thermal expansion would continue.
Wait-and-see policies work for simple systems, specifically those with short lags between detection of a problem and the implementation and impact of corrective actions. Wait-and-see policies require short delays in all the links in a long causal chain: from the detection of adverse climate impacts to the decision to implement mitigation policies; from the consequent emissions reductions to changes in atmospheric greenhouse gas concentrations; from radiative forcing to surface warming; and finally to climate impacts.
But with regard to climate change, none of these conditions hold. There are long delays in every link of the chain.
Wait-and-see policies seem logical if one assumes the climate is a simple, “first order” linear system, with short lags between detection of a problem and the implementation and impact of corrective actions. They are also advocated by reference to genuine uncertainties about how much and in what ways climate would change if the active intervention of humans accelerates or decelerates. Research should of course continue to reduce these uncertainties.
But uncertainty in no way justifies delay. You don’t know if a fire may break out in your house this coming year, or whether you will be in a car accident. That uncertainty is not a good reason for removing the smoke detectors from a house or cancelling insurance. If it turns out that you do have a fire, or accident, it will be too late to protect yourself and your family. You carry insurance precisely because there is uncertainty, not despite it.
The delays in the response of the climate to anthropogenic forcing are extremely long. If we pursue the risky experiment of continued greenhouse gas emissions growth and it turns out that the resulting climate changes are harmful, it will be too late.
Even the current proposal to stabilise emissions under the Kyoto protocol simply ensures continued growth in greenhouse gas concentrations and continued warming. The bathtub is filling twice as fast as it is draining. Can we turn down the tap before the tub overflows?
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Bathtub Basics
Why do people underestimate the time delays in the response of climate to GHG emissions? To explore this question, we presented highly educated adults enrolled in university graduate programmes with descriptions of past greenhouse gas emissions, atmospheric CO2 concentrations, and global mean temperature.
Subjects were asked to predict the behavior of CO2 levels and global temperatures in response to changes in human-generated CO2 emissions. No mathematics was required and data was drawn from the non-technical reports of the 2001 UN report of the Intergovernmental Panel on Climate Change (IPCC).
We found a widespread misunderstanding of climate change dynamics. Two-thirds of the subjects believed global temperature responds immediately to slight or dramatic changes in CO2 emissions. Still more believed that reducing emissions near current rates would stabilise the climate, when in fact emissions would continue to exceed removal, increasing greenhouse gas concentrations and radiative forcing.
Such beliefs make current wait-and-see policies seem entirely logical, but violate basic scientific principles of conservation of matter.
Low public support for policies to reduce emissions may be based more on misconceptions of climate dynamics than high discount rates (that is, putting a low value on the future) or uncertainty about the risks of harmful climate change.
If greater resources were devoted to developing public understanding of the dynamics of climate change, citizens and policymakers would have a more reliable basis for assessing current and future climate policy proposals.
See: Understanding Public Complacency About Climate Change
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This article appears as part of openDemocracy’s online debate on the politics of climate change. The debate was developed in partnership with the British Council as part of their ZeroCarbonCity initiative - a two year global campaign to raise awareness and stimulate debate around the challenges of climate change.
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